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Non-native trees have tough time hanging on through hot, dry summer; some losing branches, even dying.

September 11, 2011

2 Min Read

The heat and drought from this summer are dangerous for trees not adapted to the Kansas climate.

Ward Upham, horticulturalist with K-State Research and Extension, said the climate this summer has stressed some trees, particularly pines, spruces and firs, so much they may lose branches or die.

"To tell if a stressed tree will survive, check to see if the branch with the browning needles is alive," Upham said. After scraping off the branch bark, you should see thin green tissue, with white tissue underneath. If there is no green tissue, the branch is dead.

Upham also recommended checking ends of the branches for life. If you find many dry, brittle twigs, then at least part of the tree is probably dead.

Concentrating on good watering can reduce stress for the trees, Upham said. Trees may need watered up to once a week during hot, dry spells. You should water them to a minimum depth of 10 inches. You can test the depth by inserting a metal rod or wooden dowel into the ground. It will stop when it hits dry soil. Upham said even during the dry winter months, trees will still need to be watered about once a month, as long as the temperature is above freezing.

While the primary cause of evergreen problems this year is stress, Upham said there are other reasons trees and needles might be turning brown.

Sometimes trees that appear to be dying are just going through natural needle drop. This happens when the inside needles turn brown, while the needles on the outer branches remain green. "Natural needle drop does not harm the health of the tree," said Upham, "and is a normal process as two- to four-year-old needles are shed."

If however, all of the branches begin browning, Upham warns the tree also could be diseased. Pine wilt, affecting mainly Scots and Austrian pine, is a disease common in the Midwest where summer heat often allows the pinewood nematode to reproduce rapidly. If the majority of a tree begins turning brown, cut out a sample for your local Extension office to diagnose.

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